1. Field of the Invention
The present invention relates to xylitol compositions, and in particular, to liquid xylitol compositions that are non-crystallizing at low temperatures. The invention also relates to a co-hydrogenation process for producing liquid xylitol compositions, and a co-hydrogenation process for producing liquid xylitol compositions that are non-crystallizing at low temperatures.
2. The Related Art
The confectionary industry has long made use of xylitol as an ingredient in popular consumer products, such as chewing gums and candies. Xylitol has a sweet taste, a cooling effect in its crystalline form, and is non-cariogenic. The latter property provides a beneficial advantage of using xylitol, instead of sugar, as a sweetening agent. In fact, in some European countries and Canada, it is believed that xylitol actually repairs tooth decay. More recently, oral care companies also have begun to include xylitol in product formulations for toothpastes, mouthwashes, rinses, and the like.
Xylitol has been shown in many studies in countries outside the United States to have positive health benefits from reducing ear infections to recalcification of teeth. Many oral care and food manufacturers are exploring means to incorporate xylitol into their products.
Developers and manufacturers want the xylitol that they have incorporated into their products to remain in solution form. Many food products are stored at refrigerated and frozen storage temperatures, intentionally and unintentionally.
Xylitol is a sweetner that is as-sweet as sucrose. Crystalline xylitol, though, has a large negative heat of solution of xe2x88x9236.7 cal/g. When xylitol crystallizes in a product, the flavor profile changes and the product becomes cooling in the mouth, an objectionable characteristic in many products, such as toothpaste and fruit filings.
In many of its current applications in the confectionary and oral care industries, xylitol is employed in its crystalline (or dry) form. However, there are several disadvantages to using crystalline xylitol. Crystalline xylitol, being hygroscopic, quickly absorbs moisture and hardens, thereby making it difficult to handle. Also, the use of crystalline xylitol to produce an end product provides an added cost to that end product, since crystalline xylitol itself and its manufacturing process is expensive.
Recently, liquid xylitol has been proposed as an alternative to crystalline xylitol. The benefits of liquid xylitol are primarily in ease of handling and also potentially in cost, if the use of crystalline xylitol is avoided. Unfortunately, liquid xylitol has a tendency to crystallize out of solution, particularly at high concentrations on a dry solids basis. This makes it difficult to store liquid xylitol. Furthermore, the quality of end products can be diminished significantly. In oral care applications, for example, a crystallizing liquid xylitol will crystallize out of toothpaste and plug up tube orifices or pumps, or crystallize in a bottle or around a bottle cap in the case of rinses or mouthwashes.
U.S. Pat. No. 5,144,024 (the ""024 patent) discloses a non-crystallizing liquid xylitol composition having a dry solids content of 60-80%, wherein the dry solids are comprised of 50-90% xylitol and 10-50% non-xylitol monomeric or dimeric polyols. The non-xylitol polyols are selected from maltitol, sorbitol, mannitol, glycerol and mixtures thereof. However, unlike the present invention, the ""024 patent does not teach or suggest liquid xylitol compositions that are non-crystallizing at low temperatures. In fact, the ""024 patent discloses that liquid xylitol/sorbitol formulations at 70% dry solids comprising 70% and 80% xylitol, and at 65% dry solids comprising 80% xylitol, will crystallize after only two weeks at both 5xc2x0 C. and 10xc2x0 C. Because products are often transported through and/or stored in cold environments, it is desirable to have a liquid xylitol that remains non-crystallizing at low temperatures.
The ""024 patent teaches using a by-product stream from a xylitol crystallization process that is rich in xylitol, to make a liquid xylitol composition. In addition, the ""024 patent discloses that liquid xylitol can be made by mixing a solution of pure xylitol with a solution containing other polyols. However, as discussed above, crystalline xylitol is expensive. It desired, therefore, to have process for making liquid xylitol that does not use crystalline xylitol or employ a xylitol crystallization step.
Heretofore, it has not been possible to achieve a liquid xylitol composition that is non-crystallizing at low temperatures preferably below about 10xc2x0 C. It has also not been possible to provide a process for producing a liquid xylitol composition that does not use crystalline xylitol or employ a xylitol crystallization step.
An object of the present invention is to provide a liquid xylitol composition that is non-crystallizing at low temperatures of preferably less than about 10xc2x0 C. for at least about 3 months and preferably at least about 4 months. In one aspect, a liquid xylitol composition that is non-crystallizing at low temperatures comprises, at between about 60 and about 95% and preferably between about 65 and about 90 weight percent dry solids, xylitol, in an amount between about 60 to about 90 weight percent and preferably about 65 and about 90 weight percent of the dry solids, and sorbitol, in an amount between about 10 and about 40 weight percent and preferably between about 10 and about 35 weight percent of the dry solids. This liquid xylitol composition is preferably non-crystallizing at temperatures below about 10xc2x0 C., and more preferably between about 0xc2x0 C. and about 10xc2x0 C.
Another object of this invention is to provide a co-hydrogenation process for producing liquid xylitol compositions. In one aspect, the process comprises co-hydrogenating a sugar syrup mixture comprising a sugar syrup having a dextrose equivalence (DE) of between about 20 DE and about 99 DE, in an amount between about 5 and about 35 weight percent of the mixture, and xylose, in an amount between about 65 and about 95 weight percent of the mixture. The co-hydrogenating step takes place preferably at a temperature of between about 120xc2x0 C. and about 170xc2x0 C., and a hydrogen pressure of between about 200 psi and about 2000 psi, for between about 90 and about 180 minutes.
A further object of this invention is to provide a co-hydrogenation process for producing liquid xylitol compositions that are non-crystallizing at low temperatures. In one aspect, the process comprises co-hydrogenating a sugar syrup mixture comprising a sugar syrup having a dextrose equivalence (DE) of between about 20 DE and about 99 DE, in an amount between about 5 and about 35 weight percent of the mixture, and xylose, in an amount between about 65 and about 95 weight prevent of the mixture, to produce a liquid xylitol composition that is non-crystallizing at low temperatures. The liquid xylitol composition produced by this co-hydrogenation process is preferably non-crystallizing at between about 0xc2x0 C. and about 10xc2x0 C., and preferably comprises, at between about 65 and about 90 weight percent dry solids, xylitol, in an amount between about 65 and about 90 weight percent of the dry solids, and sorbitol, in an amount between about 10 and about 35 weight percent of the dry solids. The co-hydrogenating step takes place preferably at a temperature between about 120xc2x0 C. and about 170xc2x0 C., and a hydrogen pressure between about 200 psi and about 2000 psi, for between about 90 and about 180 minutes.
I have found that co-hydrogenated xylitol/sorbitol produced with hydrogenation process creates a means of introducing xylitol into a product, without the difficulties of incorporating crystalline xylitol into the product. Xylitol (in crystalline form) is difficult to work with because of it""s hygroscopic nature. Xylitol lumps during storage in its dry form and during incorporation. Xylitol (in its dry form) will crystallize out of products at low temperatures, creating objectionable textures in an ingestible composition such as but not limited to oral care products such as, but not limited to, toothpaste, mouth wash and embedded in the coating of dental floss and food products, such as but not limited to a form of confection, chewing gum and fruit syrup. The crystals will dissolve in the mouth and create an objectionable mouth sensation. Other co-hydrogenated xylitol/sorbitol sources can also crystallize out at cool temperatures, also causing objectionable textures and a cooling mouth sensation.
Other aspects of the present invention will be better understood and advantages thereof more apparent in view of the following detailed description of the preferred embodiments.